Boeing is using what it calls a "hard wall" in the software and has ensured no system settings can be changed in flight to stop an external input causing havoc.

With the 787 and other future aircraft expected to have this "always on-line" element to flight operations, the nightmare scenario is of terrorists remotely hijacking an airliner.

On the ground, the 787 maintenance crew will have to use codes to make system changes. "Mechanics will have to enter an authentication code before uploading software or making setting changes," says product marketing director Jim Haas.